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AC issues on '23 AT4

Exit the King

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May 17, 2025
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I'm having this weird heating/AC issues with my 23 AT4. What happens is that the heat and blower is inconsistent around 70 degrees while driving. And the AC starts on auto mode even when it's over 70 outside!

My local GMC dealer can't find an answer to it. My other GMCs work just fine, so I don't know what else to do anymore.
 
I'm having this weird heating/AC issues with my 23 AT4. What happens is that the heat and blower is inconsistent around 70 degrees while driving. And the AC starts on auto mode even when it's over 70 outside!

My local GMC dealer can't find an answer to it. My other GMCs work just fine, so I don't know what else to do anymore.
Climate controls often go crazy. I mean that. Might be worth asking your dealer to check the interior temp sensor or update the HVAC sensor. Impossible that they don't know the answer to it. That's not a rare scenario.
 
These kinds of gremlins are almost always sensor or software related. It's weird that the dealer cannot figure it out, or they don't want to bother too much, nos sure which.
 
These kinds of gremlins are almost always sensor or software related. It's weird that the dealer cannot figure it out, or they don't want to bother too much, nos sure which.
Yeah, I can confirm this about the dealers, they don't want to bother too much and usually say there's nothing wrong. If I'm not mistaken there are 3 sensors, cabin temp, outside temp and sunload. One these is probably the problem
 
the heat and blower is inconsistent around 70 degrees while driving
now, this is often tied to the automatic climate control logic
Some systems are programmed to engage AC above a certain outside temp to dehumidify the air, even if you just want a fan.
It might not be a malfunction but a design feature that's just annoying. I'm sure there's a way to disable Auto AC in the climate settings menu
 
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